From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABD843BFE37; Thu, 15 Jan 2026 17:51:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499513; cv=none; b=cZsiY4Fd3Xg3d7pku7YXm+qCtnuq/6G1zC+gykNYmRraED8j2u9xgU6DPeJ+4xXDhdWqjMoY1/Wn4EbkIsolDrWcRg+5WdLWq6/0M9HHs8aYcEaby8s6r5eYyeph0hmIxEkchjDYiX4TBIKKsDg6wmpGXzrZxO9jUlQch93NnQM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499513; c=relaxed/simple; bh=AfzBOSUV44X6Z9awrZ2GqTHWHYeMR8zg1D39qdJjipA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hXrXvPP0BjkVvmQ2RzXr0bUnGgRfw8BHVa5qDYhYve/B/S9VxzuRJBH5g1rMN2DM8tXGFLh0hZHZECsF96eb267aCiT4Ps+He6nuNHebmCSytve5XYZSGU7u0tMV+qmxbelafFyWeH55N2Q/xZ8DzGQgxDGxMP6W0QS9Ro+ST6w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Lm55/czz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Lm55/czz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0AB7C19422; Thu, 15 Jan 2026 17:51:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768499513; bh=AfzBOSUV44X6Z9awrZ2GqTHWHYeMR8zg1D39qdJjipA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lm55/czzFMPuHtEb9MIcLJPA9E42qsfS2ZIn1VEo2bRfNeCYOMaX58+8bLP1pmpmQ /vp1f1Liw7N7L5gbQq2ZCVqLAue3iyjyEPFZ6gWJ1pX/czdDphGBz2DRouCp8zw+V/ 4esrHdrnCb4MJnB4dov7XJyBm2XeaWDseA4SsbMc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sean Christopherson Subject: [PATCH 5.10 253/451] KVM: x86: WARN if hrtimer callback for periodic APIC timer fires with period=0 Date: Thu, 15 Jan 2026 17:47:34 +0100 Message-ID: <20260115164240.042652412@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164230.864985076@linuxfoundation.org> References: <20260115164230.864985076@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Christopherson commit 0ea9494be9c931ddbc084ad5e11fda91b554cf47 upstream. WARN and don't restart the hrtimer if KVM's callback runs with the guest's APIC timer in periodic mode but with a period of '0', as not advancing the hrtimer's deadline would put the CPU into an infinite loop of hrtimer events. Observing a period of '0' should be impossible, even when the hrtimer is running on a different CPU than the vCPU, as KVM is supposed to cancel the hrtimer before changing (or zeroing) the period, e.g. when switching from periodic to one-shot. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20251113205114.1647493-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/lapic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2434,7 +2434,7 @@ static enum hrtimer_restart apic_timer_f apic_timer_expired(apic, true); - if (lapic_is_periodic(apic)) { + if (lapic_is_periodic(apic) && !WARN_ON_ONCE(!apic->lapic_timer.period)) { advance_periodic_target_expiration(apic); hrtimer_add_expires_ns(&ktimer->timer, ktimer->period); return HRTIMER_RESTART;